Thermoplastic Planks and Methods For Making The Same

ABSTRACT

A thermoplastic laminate plank is described wherein the thermoplastic laminate plank comprises a core, a print layer, and optionally an overlay. The core comprises at least one thermoplastic material and has a top surface and bottom surface wherein a print layer is affixed to the top surface of the core and an overlay layer is affixed to the top surface of the print layer. Optionally, an underlay layer can be located and affixed between the bottom surface of the print layer and the top surface of the core. In addition, a method of making the thermoplastic laminate plank is further described which involves extruding at least one thermoplastic material into the shape of the core and affixing a laminate on the core, wherein the laminate comprises an overlay affixed to the top surface of the print layer and optionally an underlay layer affixed to the bottom surface of the print layer.

This application is a divisional of U.S. patent application Ser. No.09/460,928 filed Dec. 14, 1999 and is incorporated in its entirety byreference herein

BACKGROUND OF THE INVENTION

Commercially available laminate flooring (using high or medium densityfiberboard or particle board as the core layer) has gained overwhelmingsuccess in the flooring market. The growth rate of the laminate flooringhas remained in the double digits since the product was introduced inthe United States market. The success of this product is credited tocertain properties such as stain resistance, wear resistance, fireresistance, good cleanability, and the ability to use just about anytype of printed design. In addition, the overall emission of organiccompound vapor is low and the laminate flooring is considered colorstable and environmentally friendly over other competing flooringproducts.

The biggest concern with commercially available laminate flooring is themoisture resistance of the finished product and the sensitivity of theraw materials (high or medium density fiberboard, paper, and particleboard) to moisture during the manufacturing process. In some instances,the moisture can lead to some serious quality control issues andapplication restraints. For instance, and just to name a few, the highermoisture content in the product, such as in the particle board orfiberboard, can cause blistering and adhesion failure of the melaminesurface to the core. Also, higher moisture contents can lead todimensional instability of the finished product, which then results inthe cupping or doming of the product, which is extremely undesirable,especially when installers are laying down the flooring. Also, excessivemoisture contents can create edge peaking due to the swelling of theproduct and such edge peaking can result in edge chip-off or prematurewear-out or can soil more quickly. The susceptibility to moisturecontent also leads to some installers not wishing to place such laminateflooring in areas which are subject to having water on the surface ofthe floor, such as in the kitchen and bathroom areas.

The suppliers of such laminate flooring have appreciated the problemsassociated with their products and have attempted to overcome theseproblems by developing laminate flooring having better moistureresistance by using melamine, phenolic, or isocyanate binders topartially replace urea resins present in the laminate flooring. Whilethis improvement has made the product more moisture resistant, thecurrent commercially available laminate floorings are still prone tomoisture damage. For instance, the thickness swelling of laminateflooring can increase by 10% and water absorbency can exceed more than15% according to the 24 hours water absorption test. Another attemptedsolution at the moisture resistance weaknesses of current laminateflooring has led some manufactures to apply a water-repellant materialon the upper edges of the tongue and groove areas which further serve toresist any moisture penetration through joints. Still another attemptedsolution involves applying silicone caulk to seal the edges and voids ofthe laminate perimeter where the laminate flooring meets the wall.However, if very stringent installation instructions are not followed,the laminate flooring will still be subjected to moisture damage.

Accordingly, there is a need to develop a laminate flooring system whichovercomes the above weaknesses and disadvantages of current commerciallyavailable laminate flooring.

SUMMARY OF THE INVENTION

A feature of the present invention is to provide a laminate plank whichcan be used in a surface covering system which provides improvedmoisture resistance and is not susceptible to damage caused by moisture.

Another feature of the present invention is to provide a laminate plankand surface covering system which is economically feasible and permitseasy installation and flexibility.

A further feature of the present invention is to provide a flooringsystem that improves foot comfort and other ergonomic benefits.

An additional feature of the present invention is to provide a surfacecovering system having improved sound deadening and other reduced soundtransmission benefits.

Still another feature of the present invention is to provide a surfacecovering system which has significant improvements with respect to easeof installation and includes a fool-proof installation design andtechnique.

Another feature of the present invention is to provide a surfacecovering system which avoids the use of a wet adhesive applicationmethod.

Another feature of the present invention is to provide a flooring systemthat has great flexibility so as to make various shapes, sizes, andbevel edges.

Another feature of the present invention is to provide a flooring systemthat can alleviate the requirement of installing the plank in a givenorientation.

Also, a feature of the present invention is provide a surface coveringsystem which has the ability to tolerate some imperfections in thesub-floor or substrate and thus avoid telegraphing the imperfections onthe surface covering itself.

A further feature of the present invention is to provide a surfacecovering system which has improved damaged resistance properties, suchas improved impact strength and the like.

Additional features and advantages of the present invention will be setforth in the description which follows, and in part will be apparentfrom the description, or may be learned by practice of the presentinvention. The features and other advantages of the present inventionwill be realized and attained by means of the elements and combinationsparticularly pointed out in the written description and appended claims.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described herein, thepresent invention relates to a thermoplastic laminate plank, wherein thelaminate plank has a core comprising at least one thermoplasticmaterial, wherein the core has a top surface and a bottom surface.Optionally affixed to the top surface of the core can be a print layer,wherein the print layer has a top surface and a bottom surface. Also, anoverlay layer is affixed to the top surface of the print layer. Theplank can optionally contain an underlay layer located and affixedbetween the bottom surface of the print layer and the top surface of thecore.

The present invention further relates to a method of making athermoplastic laminate plank and involves the step of extruding at leastone thermoplastic material into the shape of a core and optionallyaffixing a laminate on the core, wherein the laminate comprises anoverlay layer affixed to the top surface of a print layer and optionallyan underlay layer affixed to the bottom surface of the print layer.

Also, the present invention relates to a method of making athermoplastic plank by printing a design directly on the top surface ofthe plank using any number of printing techniques, such as gravureprinting, transfer printing, digital printing, Flexo printing, and thelike. The method includes applying a protective coating on top of theprinted design, such as a polyurethane type coating with or without wearresistant particles in the coating.

A further embodiment of the present invention relates to making athermoplastic plank for flooring by co-extrusion techniques, whichinvolves extruding at least one thermoplastic material into the shape ofthe core and also extruding a layer containing at least onethermoplastic material with one or more pigmented compounds on top ofthe extruded core, wherein the layer simulates a design, such as woodgrain.

The present invention also relates to thermoplastic planks having theabove-described characteristics.

It is to be understood that both the forgoing general description andthe following detailed description are exemplary and explanatory onlyand are intended to provide further explanation of the presentinvention, as claimed.

The accompanying drawings, which are incorporating in and constitute apart of this application, illustrate several embodiments of the presentinvention and together with the description serve to explain theprinciples of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing a side view of one embodiment ofthe thermoplastic laminate plank of the present invention.

FIG. 2 is a schematic diagram showing a side view of a spline designwhich can be used in the present invention.

FIG. 3 is a schematic diagram of a sectional view showing anotherembodiment of a thermoplastic laminate plank of the present invention.

FIG. 4 is a schematic diagram showing a groove design for a plank of thepresent invention.

FIGS. 5 and 6 are schematic diagrams showing sectional views ofadditional embodiments of the thermoplastic laminate plank of thepresent invention.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

In general, the present invention relates to a thermoplastic laminateplank which contains a core comprising at least one thermoplasticmaterial. This core has a top surface, a bottom surface, and at leastfour sides or edges. Located or affixed on the top surface of the coreis a print layer where the print layer has a top surface and a bottomsurface. Optionally located or affixed onto the top surface of the printlayer is an overlay layer having a top surface and a bottom surface. Thethermoplastic laminate plank of the present invention can optionally andfurther contain an underlay layer which is located and affixed betweenthe bottom surface of the print layer and the top surface of the core.

In more detail, the core in the thermoplastic laminate plank is made ofat least one thermoplastic material. Generally, any thermoplasticmaterial, combinations thereof, alloys thereof or mixtures of two ormore thermoplastics can be used to form the core. Generally, suchthermoplastic materials include, but are not limited to, vinylcontaining thermoplastics such as polyvinyl chloride, polyvinyl acetate,polyvinyl alcohol, and other vinyl and vinylidene resins and copolymersthereof; polyethylenes such as low density polyethylenes and highdensity polyethylenes and copolymers thereof; styrenes such as ABS, SAN,and polystyrenes and copolymers thereof; polypropylene and copolymersthereof; saturated and unsaturated polyesters; acrylics; polyamides suchas nylon containing types; engineering plastics such as acetyl,polycarbonate, polyimide, polysulfone, and polyphenylene oxide andsulfide resins and the like. One or more conductive polymers can be usedto form the plank, which has applications in conductive flooring and thelike. The thermoplastic polymers set forth in Kirk Othmer (3^(rd)Edition, 1981) at pp. 328 to 848 of Vol. 18 and pp. 385-498 of Vol. 16,(incorporated in their entirety by reference herein) can also be used aslong as the resulting plank has sufficient strength for its intendedpurpose.

Preferably, the thermoplastic material is a rigid polyvinyl chloride butsemi-rigid or flexible polyvinyl chloride may also be used. Theflexibility of the thermoplastic material can be imparted by using atleast one liquid or solid plasticizer which is preferably present in anamount of less than about 20 phr, and more preferably, less than 1 phr.A typical rigid PVC compound used in the present invention to form thecore can also include, but is not limited to, pigments, impactmodifiers, stabilizers, processing aids, lubricants, fillers, woodflours, other conventional additives, and the like.

The thermoplastic polymer compound to be processed can be in powder,liquid, cubed, pelletized form and/or any other extrudable form. Also,the thermoplastic polymer can be virgin, recycled, or a mixture of both.Furthermore, the thermoplastic material can be incorporated with ablowing agent(s) or a mechanically injected gas during the extrusionprocess to make a cellular foam structure core.

The thermoplastic material used to form the core, which is preferablypolyvinyl chloride, is preferably a suspension grade or masspolymerization grade homopolymer resin having a preferred molecularweight as reflected by an inherent viscosity of from about 0.88 to about1.0 inherent viscosity. In general, a higher molecular weight polymer ispreferred from the standpoint of processing stability and preferably themolecular weight distribution and particle size distribution are narrowin order to provide a good balance between processability andproperties. Also, high porosity and uniform porosity of the resinparticles are preferred to optimize compounding and processing aspects,including the fast and uniform absorption of any stabilizer that ispresent as well as other ingredients during compounding.

Preferably, the thermoplastic material used to form the core is a rigidPVC powder compound that has good impact strength, ease of processing,high extrusion rate, good surface properties, excellent dimensionalstability, and indentation resistance.

The preferred thermoplastic polymer used to form the plank is apolyvinyl chloride from The Geon Company designated X150-206-050-02,which has the following formula:

FORMULATION PARTS BY WEIGHT Extrusion Grade PVC (0.88-0.96 IV) 100 TinMercaptide Stabilizer 2-4 PVC Acrylic Processing Aid 1-3 Filler 10-30Impact Modifier (Acrylic)  3-10 Lubricant Package 2-5 Pigment 1-5

The polyvinyl chloride preferably has the following properties:

GEON COMPOUND ASTM METHOD 87150 Type Cube Cell Classification D178413344-C Specific Gravity 0.2 D792 1.45 Hardness-Durometer Shore D 3D2240 82 Tensile Properties - Strength PSI D638 6000 TensileProperties - Modulus PSI D638 390000 Flexural Properties - Strength PSID790 11000 Flexural Properties - Modulus PSI D790 370000 Heat DeflectionTemperature F. D648 160 Unannealed @ 1.82 MPa (264 PSI) Coefficient ofLinear Expansion D696 3.4 × 10 − 5 in./in. F. Notched IZOD Ft. lb./in.of notch @ D256 3 23 C. (73 F.) Impact Properties - Drop Impact D42261.0 in. lb/mil @ 375 F. melt T. 1.0 ¼″ Dart H.250 Method A 1.0 ¼″ DartH.250 Method B 1.0 ⅛″ Dart H.125 Method A ⅛″ Dart H.1250 Method B

Generally, this compound will have a melt temperature of from about 360to about 390° F. Preferably, a stabilizer is also present in thethermoplastic formulation that forms the core. A preferred stabilizer isa butyl tin mercaptide stabilizer. In addition, an impact modifier isalso preferably present and preferred impact modifiers are acrylic-basedfrom Rohm and Haas, an EVA-based impact modifier known as Elvaloy™ fromDuPont; and others such as chlorinated polyethene and acrylonitrilebutadiene styrene, and the like.

In addition, the thermoplastic formulation preferably contains at leastone processing aid which is preferably an acrylic based low molecularweight resin such as Acryloid K-125 or K-175 from Rohm and Haas. Also,at least one lubricant is preferably present and more preferably aninternal lubricant and an external lubricant. Preferred internallubricants, which act internally to alter the cohesive forces amongstthe polymer chains that results in lower melt viscosity without reducingthe strength properties of the resin, are metallic stearates such ascalcium and zinc salts of stearic acid. External lubricants, which actexternally to prevent resins from sticking to hot metal processingmachinery by reducing friction between the services, are preferablylow-melting paraffins. Fillers are preferably added to the thermoplasticformulation to reduce product cost and to improve impact properties.While any filler can be used as long as it is compatible with thethermoplastic resin, typical fillers include, but are not limited to,calcium carbonate.

Preferably, the thermoplastic core is rigid in nature and has thefollowing range of preferred properties: impact resistance, static loadresistance, indentation resistance, moisture insensitivity, pre-profiledconfiguration, and the like.

While the core can be made in a number of ways, preferably the core isformed by an extrusion process wherein the thermoplastic material alongwith any other optional ingredients are blended together and are thenfed into an extruder by a feeder wherein the extruder with theapplication of heat and auger action melts the thermoplastic material tothe extent that it is eventually fed through a die, wherein the die isin the shape of the core.

In more detail, the extrusion process permits a) an economicallyfeasible design by designing a profile with cavities inside thestructure and b) a highly versatile method of achieving the complicatedprofile design of the preferred plank without additional machiningafterwards for the tongue and groove, for instance. While any extrudercan be used which can extrude the desired design of the plank forthermoplastic materials, preferably the extruder is one from AmericanMaplan corporation such as model TS-88 which has the ability to processrigid PVC profiles with an maximum output capacity of about 900 lb/hr,based upon a compound bulk density of 37 lb/ft³. The TS-88 is a twinscrew extruder which has a barrel heating section and a cooling sectionas well as a vacuum system. In the extruder, there can be 12 temperaturezones with 6 for cooling and a temperature control system.

The dimensions of the core can practically be any shape or size as longas such material can be extruded as one piece or multiple pieces. Forinstance, the core preferably has a thickness of from about 3 mm toabout 50 mm, a width of from about 2 cm to about 60 cm, and a length offrom about 30 cm to about 215 cm. Also, the top surface of the core canoptionally have a textured surface on the top surface as part of thecore which is extruded through the die. A mechanical embossing row canbe located behind the cooling calibrator and after the extrusion die toachieve surface texturing of the extruded core. Any variety of texturescan be created by this method on the core such as wood grains and thelike.

Also, as an option, the core can be 100% solid or can have one or morecavities or cells which are located between the upper and lower surfacesof the core. While the cavities are optional, the cavities are preferredsince they reduce the amount of thermoplastic material used and create alighter weight product. The cavities or cells which can be part of theextruded core preferably have cavities having dimensions of from about 3mm to about 16 mm in height, by about 6 mm by about 20 mm in width, andcan be separated by solid thermoplastic material having a thickness offrom about 1.0 mm to about 3.02 mm. The optimal dimension of cavities isdependent upon the requirement of the product withstanding the potentialimpact force of falling objects. The cavities which are preferablypresent can be any shape such as rounded, oval, or rectangular. Thesecavities or cells preferably exist across the entire distance of thecore as shown in FIGS. 1, 5, and 6. Another advantage is that wires,cables, fiber optics, and/or piping can be run through the cavitieswhich makes installation of wiring and piping quite easy without thenecessity of putting holes through walls, or running wires underneaththe floor or in the ceiling. Further, if necessary, holes can be drilledthrough the thermoplastic material separating one cavity from another inorder to have the wire or piping go in a perpendicular direction whennecessary. Alternatively, for certain thermoplastic core pieces, thecavities can be run in a perpendicular direction from the remainingpieces in order to accommodate the direction that wiring or piping maytake when being placed in a room.

The cores which form the plank are preferably all made from the same diedesign and thus they are uniform in appearance. Also, the cavities whichare preferably present in the core align with the cavities in respectivecore pieces. Dowels or other equivalent material can be inserted intothe cavities at the short end of the plank in order to join an adjacentplank to create a tight seal at each seam. This type of coupling system,though optional, will further insure a very secure tight fittingfloating floor or other surface covering.

Though not necessary, the ends of the plank as well as the tongue and/orgroove can have a bonding agent applied to these locations in order toseal or bond the planks together. Surprisingly, the inventors havediscovered that sealant compositions such as tetrahydrofuran have theability to actually work as a bonding agent to join the planks together.In one of the examples that follows, the results show that by usingtetrahydrofuran or compositions like tetrahydrofuran, the joints of theplanks which have been attached with the use of this composition leadsto the formation of a bond between the planks and increases the overallbond strength of two adjoining boards significantly. The use of thisbonding agent can be used not only with the planks described above butwith all thermoplastic planks. One advantage of using a bonding agentlike tetrahydrofuran is that it is environmentally safe, it is simple touse and leaves no residue on the surface after evaporation. Thus, noadhesive marks are left on the surface of the planks. In addition,applying such bonding agents like tetrahydrofuran is quite easy since itcan be applied by brush or spray or applicator tip using gravity orother force such as squeezing an applicator bottle, and any excess iseasily removed unlike the application of some adhesives for tiles andthe like. Other examples of other suitable bonding agents which havethis ability to bond the thermoplastic planks include, but are notlimited to, methylene chloride and ketones and the like. Examples ofketones include, but are not limited to methyl ethyl ketone, methyl amylketone, dipropyl ketone, methyl isobutyl ketone, n-methyl pyrrolidone,dimethyl formamide, cyclohexanone, nitrobenzene, and the like.

Another optional aspect of the core is the presence of a groove and/or atongue design on preferably two sides or edges of the core wherein thesides or edges are opposite to each other. While the core design canhave a tongue design on one edge and a groove design on the oppositeedge, it is preferred that both edges which are opposite to each otherhave a groove design. This tongue and/or groove design on the core canbe formed as part of the extruded core. The tongue or groove can have avariety of dimensions but preferably the groove which is present on two,opposite edges has internal depth dimension of from about 5 mm to about12 mm and a height of from about 3 mm to about 5 mm. The bottom width ofthe side having the groove is slightly shorter than the upper width ofthe same side to ensure no gap exists between planks after buttingtogether. In addition, it is preferred that the groove have teethlocated on the upper surface and lower surface of the groove to receivean interlocking tongue, wherein the tongue is a separate component whichwill be described later. The teeth which can preferably be present aspart of the extruded groove forming part of the extruded core arepreferably from about 0.7 mm to about 1.2 mm in size for each tooth andhaving an angle of from about 30 to 45 degrees with a backward biteenabling more easy insertion than removal of the tongue portion. Apreferred design is set forth in FIGS. 3 and 4.

Also, as an option, any edge, and preferably the edges which preferablyhave the tongue and/or groove are preferably tapered or beveled so thatwhen two cores are brought together for attachment, a valley or V-shapedvalley is formed. Preferably, the tapered or beveled edges are at anangle of from about 15° to about 55°, and more preferably at about a 17°angle. Also, the length of the beveled or tapered edge is about 2.0 mmto about 7.0 mm on each core piece. A preferred design is set forth inFIG. 3.

As another option, the core can have located on its bottom surface anynumber of bottom feet which are preferably pieces of rubber orthermoplastic material which are attached to the bottom surface of thecore. Preferably, the bottom feet are thermoplastic material and morepreferably are soft thermoplastic material which are post-extruded ontothe bottom surface of the plank. While the bottom feet can have anydimensions, preferably the bottom feet have an outer dimension of fromabout 1.0 mm to about 5.0 mm. The bottom feet provide numerous functionssuch as increasing the soft, cushion feeling of the plank to improvefoot comfort level and also reduces the problems associated withsub-floor or substrate imperfections. The bottom feet can also assist incontrolling sound transmissions, and thus have sound deadeningproperties. Also, the bottom feet insure that migration from any mold,mildew, and/or stain which may be part of the sub-floor or substrate canbe minimized if not eliminated by the bottom feet.

As an additional option, the product with bottom feet can be installedup side down to make a slip resistance floor for such applications asescalators or stairways.

The bottom feet are located on the bottom surface of the core and can beinstalled using serrations or a series of linear grooves which can beformed as part of the extruded core and then these serrations can thenbe subsequently post extruded with a line of post extruded softpolymeric material which fills in the serration and extends beyond thebottom surface of the core to support the core above a sub-floor orsubstrate. Typically, the post extruded material extends beyond thebottom surface from the core by about 10 mils to about 75 mils, and morepreferably from about 25 mils to about 50 mils. FIGS. 1, 3, 5, and 6further show embodiments of how the post extruded lines of thermoplasticmaterial can serve as a support mechanism.

With respect to the laminate on top of the core, a print layer isaffixed to the top surface of the core, wherein the print layer has atop surface and a bottom surface. The print layer preferably is anaminoplast resin impregnated printed paper. Preferably, the print layerhas a printed design. The printed design can be any design which iscapable of being printed onto the print layer. The print layer is alsoknown as a decor print layer. Generally, the print layer can be preparedby rotogravure printing techniques or other printing means such asdigital printing. Once the paper has the design printed on it, the paperis then impregnated with an aminoplast resin or mixtures thereof.Preferably the aminoplast resin is a blend of an urea formaldehyde and amelamine formaldehyde.

The print paper, also known as the Deco paper, preferably should havethe ability to have liquids penetrate the paper such as a melamineliquid penetrating in about 3 to 4 seconds and also maintain a wetstrength and even fiber orientation to provide good reinforcement in alldirections. Preferably, the resin used for the impregnation is a mixtureof urea formaldehyde and melamine formaldehyde resins. Urea formaldehydecan contribute to the cloudiness of the film that is formed and thus isnot preferred for dark colors and the melamine resin impartstransparency, high hardness, scratch resistance, chemical resistance,and good formation, but may have high shrinkage values. Combining urearesins with melamine resins in a mixture or using a double impregnation(i.e., applying one resin after another sequentially) provides apositive interaction in controlling shrinkage and reducing cloudiness.Preferably, the type of paper used is 75 g/m² weight and having athickness of 0.16 mm. The saturation of the coating preferably is about64 g/m².

Located optionally on the top surface of the print layer is an overlay.The overlay which can also be known as the wear layer is an overlaypaper, which upon being affixed onto the print layer, is clear inappearance. The overlay paper is preferably a high abrasive overlaywhich preferably has aluminum oxide embedded in the surface of thepaper. In addition, the paper is impregnated with an aminoplast resinjust as with the print layer. Various commercial grades of high abrasiveoverlays are preferably used such as those from Mead Specialty Paperwith the product numbers TMO 361, 461 (70 gram/m² premium overlay fromMead), and 561 wherein these products have a range of Taber values of4000 to 15000. The type of paper preferably used is about 46 g/m² andhaving a thickness of about 0.13 mm.

With respect to the print layer and the overlay, the amount ofaminoplast resin is preferably from about 60 to about 140 g/m² and morepreferably from about 100 to about 120 g/m².

As an option, an underlay can be located and affixed between the bottomsurface of the print layer and the top surface of the core. Preferablythe underlay is present and is paper impregnated with an aminoplastresin as described above with respect to the print layer and overlay.Preferably, the underlay is Kraft paper impregnated with aminoplastresins or phenolics and more preferably phenolic formaldehyde resin ormelamine formaldehyde resin which is present in an amount of from about60 g/m² to about 145 g/m² and more preferably from about 100 g/m² toabout 120 g/m² paper. The type of paper used is preferably about 145g/m² and having a thickness of about 0.25 mm. The underlay is especiallypreferred when extra impact strength resistance is required.

Preferably, the thermoplastic laminate plank can be prepared byextruding the core as described above and forming a laminate comprisingthe overlay affixed to the top surface of the print layer and optionallythe underlay layer with which is affixed to the bottom surface of theprint layer. This laminate can be prepared by, for instance, any processcustomarily used to manufacture laminate films such as a continuousdouble belt press. In general, the underlay, if used, the print layerand the overlay can be fed into a continuous double belt press thatserves as a laminating calendar. Preferably, the continuous operation isan isobaric system wherein pressures can go as high as 30 bar and theline speed can be up to 20 meters per minute. The pressure zone lengthis about 2-3 meters. In this continuous double belt press system, theisobaric system provides a steady uniform pressure effect on each pointof the treated surface of the laminate. Embossing of the laminate can beaccomplished by embossed release paper or the belt of the double beltpress can be embossed to produce surface textures. In a continuousdouble belt press, the simultaneous heating of the laminate with properdwell time and pressure forms the laminate film which then can be rolledup for subsequent application. Once the laminate is formed it can beapplied onto the core and is preferably affixed by any means, such aswith an adhesive. Preferably the adhesive is a hot melt adhesive such asa hot melt glue like hot melt polyurethane glue.

The hot melt adhesive, such as the hot melt polyurethane adhesive, ispreferably applied to the back surface of the laminate film at apreferred temperature of from about 250° F. to about 300° F., morepreferably from about 250° F. to about 275° F. These temperatures mayvary slightly depending upon the adhesive. The application of the hotmelt adhesive to the laminate can be done by a direct roll coater. Thelaminate with the adhesive on the back surface can then be heated to anadequate temperature to soften the laminate and allow the laminate toform to the profile of the thermoplastic core and thus be affixedpermanently. The typical wrapping machine is designed to hold thelaminate to the contour of the thermoplastic plank as it is being cooledbelow about 90 to about 100° F. The thickness of the application of theadhesive can have an effect on the impact resistance of the finishproduct. If the application of the adhesive is too thick, an impact maycause the laminate to become brittle and crack. A thin applicationenables the laminate to flex less during impact and minimize the damage.Application of the adhesive is preferably from about 5 to about 15 g/ft²and more preferably from about 6 about 12 g/ft². A preferred hot meltadhesive is Ever-Lock® 2U145/2U230 modified polyurethane adhesivereactive hot melt from Reinhold Chemicals, Inc.

As described early, the various laminate planks of the present inventioncan be connected together by a tongue piece or spline or snap connector.A separate spline or snap connector is a separate piece and isespecially effective when a groove is present on two, opposite sides oredges of the thermoplastic laminate plank. The snap or tongue piece canbe inserted into one groove and is long enough to extend outside thegroove and fit into a respective groove of another thermoplasticlaminate plank in order to connect the two pieces together. Preferably,the tongue piece or snap connector is a co-extruded material that ismade of a rigid thermoplastic material such as polyvinyl chloride orpolyvinyl chloride/rubber blends in the central portion and a softthermoplastic material such as soft polyvinyl chloride wherein the softthermoplastic material is at the top and bottom surface of the snapconnector in order to be flexible when inserted into the groove so as tofit securely to the teeth portions of the groove in the preferredembodiment.

In the present invention, while each of the thermoplastic laminateplanks can be affixed to the sub-floor or substrate, it is preferredthat the thermoplastic laminate planks be attached only to each otherthrough the groove system such that there is a floating floor system.This promotes fast and easy laying of the floor system.

With the thermoplastic laminate planks of the present invention, thepresent invention achieves many benefits and advantages such as moistureresistance and mechanical properties such as impact strength, resistanceto indentation and gouges, and beneficial acoustical properties.Further, the laminate plank system of the present invention can be usedin any environment, dry or wet, indoor or outdoor since it is notsusceptible to moisture. In an embodiment of the present invention, theplanks are less sensitive to the combined effects of temperature andhumidity than is the standard laminate product. As a result, the needfor T-moldings to act as expansion and contraction areas of the floorcan generally be eliminated. These T-moldings are not only unsightly,but can act as tripping hazards. By the elimination ofT-moldings/expansion joints in the walkway, the present invention allowsthe use of the floor in commercial applications. In an embodiment, thepresent invention expanded only one fifth as much as a standard laminateproduct under identical conditions. These conditions take the productfrom ambient room conditions to conditions of 100% relative humidity and90° F. Standard expansion joints for laminate are typically placed every30 feet. Thus, a hallway of 150 feet would be feasible without anexpansion joint with the present invention.

A second study shows that by post conditioning the planks, such as at240° F. for varying times of from 20 to 40 seconds, the planks may berendered even more stable. This treatment is referred to as thermalbalancing. Results are described in the table below.

Description of Flooring Growth in Width** Growth in Length** Plank #1*0.03% 0.03% Plank #2* 0.03 0.03 Plank #3* 0.04 0.03 Laminate Plank(Comparison) 0.10 0.20 (Commercial product) *present invention**Conditions start at ambient room conditions. Product expands duringchange to 90° F. and 100% RH.

Also, in the preferred embodiment of the present invention, theinstallation method used as a result of the unique designs of thethermoplastic laminate planks of the present invention preferablyeliminates the glue used for tongue and groove connections.

In the preferred embodiment of the present invention, the installationmethod utilizes the unique design of the product to eliminate the needfor glue used in tongue and groove connections.

Furthermore, the installer has options for installing the thermoplasticlaminate plank product. In one method, a floating floor installationmethod can be utilized. In this method, no adhesive is applied to bondthe product to the subfloor surface. The benefits of this method havebeen described earlier.

In a second method, a full-spread adhesive is applied between theunderside of the product and the sub-floor surface. This provides theadvantages of added dimensional stabilization and sound deadening. Bothof these properties would be beneficial in commercial applications.

In addition, the excellent moisture resistance and sound deadeningqualities of this product can eliminate the need for underpadding,though use of underpadding is an option.

A further embodiment of the present invention relates to a thermoplasticplank which comprises the same plank described above but, in lieu of alaminate on top of the plank, a design is printed directly on the topsurface of the plank using any number of printing techniques such asgravure printing, transfer printing, digital printing, flexo printing,and the like. Or, a printed thermoplastic film (e.g., PVC) or a woodveneer and the like can be laminated to a thermoplastic plank. Aprotective coating can then be placed on top of the printed design. Anytype of protective coating or wear layer can be used such as apolyurethane type coating with or without wear resistant particles inthe coating. Thus, a thermoplastic plank would comprise a corecomprising at least one thermoplastic material where the core has a topsurface and bottom surface as well as opposing sides and a printeddesign directly on the top surface of the plank and optionally at leastone protective coating on top of the printed design. The top surface ofthe plank as described earlier, can have a textured surface as describedabove.

This type of thermoplastic plank can be made by extruding at least onethermoplastic material into the shape of the core and then printing adesign directly on the top surface of the plank and then optionallyapplying at least one protective coating on top of the printed designand curing the protective coating. The protective coating can be appliedby conventional techniques, such as curtain coater, direct roll coater,differential roll coater or air knife coater or spray apparatus.

In another embodiment of the present invention, a thermoplastic plankfor surface coverings, such as flooring, has a thermoplastic core asdescribed above in the other embodiments and a extruded layer on the topsurface of the core wherein this extruded layer comprises at least onethermoplastic material with one or more pigmented compounds. Thisextruded layer on top of the extruded core can simulate various designssuch as wood grain and the like.

The thermoplastic plank in this embodiment can be made by co-extrusiontechniques which involves extruding at least one thermoplastic materialinto the shape of a core and extruding either simultaneously orsubsequently a layer containing at least one thermoplastic material withone or more pigmented compounds on top of the extruded core.

Another embodiment involves a thermoplastic plank having the same designas described above with a printed polymeric film, such as a PVC filmplaced on the top surface of the extruded core. The printed polymericfilm can be a polymeric film having a printed design on the film whereinthe film would preferably be from about 10 to about 20 mil thick. One ormore wear layers or protective coatings can be placed on top of theprinted polymeric film. The polymeric film can be placed on top of theextruded core by typical lamination techniques such as heating theprinted film, then pressing the film to the extruded core to bond themtogether, or using glue to bond them together.

In more detail and with reference to the Figures, the Figures showvarious aspects of several embodiments of the present invention. Withreference to FIG. 1, FIG. 1 represents a schematic diagram of a sideview of one embodiment of the thermoplastic plank. The particular Figureis with the prospective view of looking at the front edge of thethermoplastic plank wherein the groove (76) would run along each edge ofthe plank. The spline or tongue (64) is inserted along the length ofeach groove (76). (72) points to the edges of the spline having thegroove whereas (68) points to the lower or bottom surface of the splineand (70) points to the top surface or the surface that typically butoptionally receives the print layer and the like. (62) refers to thefeet or strips of post-extruded material which extends along the bottomsurface of the core from the front edge to the back edge. As can be seenin FIG. 1, typically these post extruded lines of thermoplastic materialact as a support mechanism and typically run parallel in the sameparallel direction as the cavities (60). Preferably, and as shown in theembodiments in FIG. 1, the side of the plank which has a groove istypically tapered or beveled (78).

Referring to FIG. 2, FIG. 2 is a representation of one type of spline ortongue (64) that can be used in one embodiment of the present invention.As can be seen in FIG. 2, the preferably soft material (82) such as PVCis located on the top and bottom surface of the spline or tongue inorder to ensure a tighter fit with the groove of the thermoplasticplank. The spline design preferably has a thickness of from about 3 milsto 5 mils thicker than the groove of the plank. If the spline is toothick, it can open the groove and cause edge peaking. If the spline istoo thin, it does not effectively engage the groups with the teeth inthe groove. The edges of the spline or tongue (64) are tapered orbeveled (80) in order to ensure that the tongue can be inserted into thegroove.

FIG. 3 makes reference to a spline (64) which has teeth (90) on thesurfaces which engage the groove (76) of the thermoplastic plank.Further, as can be seen in FIG. 3, in a to preferred embodiment, the topsurfaces of the plank form a V shape valley (88) and the edge of theplank touches each other whereas the bottom portions of each respectiveplank are cut in order to have a slightly shorter length in order toform a gap (86) which ensures that the top ends (88) touch each otherand do not leave any gaps on the walking surface of the planks. (84)shows a top layer(s), such as a print layer and the like.

Referring to FIG. 4, FIG. 4 is a depiction of a tongue (76) which hasreceiving teeth (92) for a spline or tongue of the design shown in FIG.3 (90). FIG. 4 further shows the post extruded lines on the bottomsurface of the extrusion plank (62) as well as the various angles andcuts of the cavity (60) as well as the receiving groove (76). Further,the beveled or tapered edge (78) is further shown in FIG. 4.

FIGS. 5 and 6 represent various different widths of the plank butgenerally the same features as shown in FIG. 1 and the numbers in FIGS.5 and 6 represent the same features.

The thermoplastic planks of the present invention can be used in avariety of applications including, but not limited to, wall panels,ceiling panels, flooring surfaces, decks, patios, furniture surfaces,shelving, and other surface coverings or parts thereof.

The present invention will be further clarified by the followingexamples, which are intended to be purely exemplary of the presentinvention.

EXAMPLES Example 1

Compound:

In one case a PVC compound containing impact modifier, filler,stabilizer and processing aids in the amounts below was extruded througha profile die giving a hollow cross section as shown in FIGS. 1, 5,and/or 6.

Ingredient Amount (phr) PVC Homopolymer 100 Thermal Stabilizer 0.8-1.5Processing Aid 0.5-1.0 Impact Modifier 3.0-4.0 Lubricant internal0.6-1.0 external 1.1-1.5 Filler 20-35 TiO₂ 1.5-3.0

Extrusion Conditions: (See Figure for diagram of locations)

Barrel Barrel Barrel Barrel Barrel 1 2 3 4 5 Barrel Temper- 345-360345-360 320-340 315-330 90-110 atures, deg F. Oil Temperature 285-300(through screw) Die 1 Die 2 Die 3 Die 4 Die 5 Die Temper- 345-360360-370 360-370 380-390 370-380 atures, deg F. Percent Load 63-75% MainRPM 950-1100 Output 356-550 pounds/hr (163-250 kg/hr) Back Pressure18.1-19.0 metric tons Melt Pressure 4,075-4500 psi Melt Temper- 385-390ature, deg. F. Color Feeder 0.35-0.70 pounds/hr setting of 5 for 0.35,setting of 10 for 0.70 Line Speed 8.5-8.75 feet/min Calibration Unit:Vacuum 1 16-20 in Hg Vacuum 2 17-20 in Hg Vacuum 3 12.5-15.0 in HgVacuum 4 off Puller Force 3560-4000 pounds Water Temper- 61 ature, degF. Pressure at Cooling and Sizing, psi #1 40 mbar #2 40 mbar ClampingPressure at conveyor Front 40-45 psi Back 28-35 psi Counter- 33-40 pisbalance

Specific Applications Wrapping Conditions: Layout of Line/Conditions:

A machine was used to form the HPL (High Pressure Laminate top layer)onto the PVC Plank Base. The machine was called a “wrapping machine” andis composed primarily of two main parts 1) a forming action to shape theHPL to the contour of the base, and 2) a clamping action to retain theHPL shape onto the base as the adhesive cools and strengthens.

In more detail:

1. PVC Planks were placed onto the line to be conveyed through by rubbercovered roller wheels. Speed of conveyance was 35-50 feet per minute inthis particular application. In other application, speeds may range ashigh as 120 fpm.2. PVC Planks underwent surface treatment to raise surface tension andimprove the wetting of adhesive onto the surface. The surface treatmentunit which was from Corotec, 145 Hyde Rd, Farmington, Conn.), providedplasma jet treatment. The surface tension was raised from 34 to45+dyne-cm.3. HPL (laminate) top layer, dispensed in a continuous roll, was treatedwith a polyurethane hot melt adhesive, Reichold 2U145, available fromReichold Chemicals, 2400 Ellis Rd, Durham, N.C. The adhesive was heatedto 237 degrees F. and rolled onto the back of the HPL layer with aknurled roll.4. The HPL was then mated to the PVC Plank, and IR heat was directedonto the face of the HPL. Temperature on the face of the PVC Plank wasraised to 300° F. −330° F., which softens the HPL enough to allowshaping.5. The HPL was shaped using rubber rollers onto the face of the PVCplank and down the beveled edges of the plank. As such, this wrappingprocess shaped the HPL to adhere to the topography of the plank ontowhich it is being affixed.6. Water spray quickly lowered the temperature of the HPL/PVC Plankassembly to below 100° F. (94 F). Rubber rollers continued to hold theHPL onto the PVC surface while the assembly cooled further. This allowedthe adhesive to cool and strengthen, thereby permanently affixing theHPL top layer to the PVC Plank lower layer.7. Each individual plank assembly was then separated from the followingplanks with a force appropriate to make a sharp separation.

Post-Treatment: Mechanical Post-Treatment

The HPL/PVC Plank assembly was then finished with tendon and edgingprocedures to cut the board ends square and trim the laminate overhangflush to the base plank.

Thermal Post-Treatment

Due to the uneven top-side heating of the HPL/PVC Plank assembly duringshaping, the finished product can develop a “cup” distortion where thetop ends of the plank come closer together. In order for the plank tolie flat, this must be countered with an opposing thermal treatment onthe back side of the HPL/PVC Plank Assembly. Thermal treatment can bedone in line by directly heating (in an upward direction) the bottomsurface of the plank while the plank is undergoing the wrapping process.

For the specific HPL/PVC Plank geometry shown in FIG. 1, it has beenfound that by heating the back surface of the assembly to certaintemperatures for certain times, the shape of the board can becontrolled. In fact, the cupping can be corrected and a flat plankproduced if the board is heated to 240-300 degrees F. for 20-45 seconds.

If the board is allowed to reside at higher temperatures for longertimes, a “doming” can actually be induced into the board. So totalcontrol of the ultimate shape of the board can be achieved byappropriate selection of conditions.

The thermoplastic plank of the present invention was tested forproperties and compared to commercially available Mannington laminateand wood flooring products.

The can drop test involved dropping a 2 lb can from 40 inches high,wherein 100% means a chip off of the product and 0% means no chip off.

Extrusion Plank Testing Mannington Product Extrusion Plank TestDesignation Laminate Wood Plank Only With Overlay Taber Abrasion, cyclesto IP 9880 125 5 mils @ 500 5590 Can Drop, mils indent MD, no feet 30,100% cat 50, 100% cat 5, 16% cat  5, 0% cat AMD, no feet 30, 100% cat31, 100% cat 1, 0% cat 1, 0% cat MD, with feet — — 7, 28% cat  5, 60%cat  AMD, with feet 1, 0% cat 0, 0% cat Pneumatic Indent, mils indent Nofeet 0 3.6 0.2 0 With feet — — 0.2 0.2 Two hour stain KC-261 Asphalt(Sealer) 0.5 0 3 0 Shoe Polish 0 1 0 0 Oil Brown 0.5 0 0 0 Mustard 0 0 00 Chemlawn 0 0 0 0 Blue Sharpie 0.5 0.5 0.5 0 Iodine 0 3 0 0 Total Stain1.5 4.5 3.5 0 Static Load, mils indent No feet 0 1 0 0 With feet — — 0 0Sliding Gouge MD, no feet 250 psi pass pass pass pass 300 psi pass failpass pass 350 psi pass fail pass pass AMD, no feet 250 psi pass passpass pass 300 psi pass fail pass pass 350 psi pass fail pass pass MD,with feet 250 psi — — pass pass 300 psi — — pass pass 350 psi — — passpass AMD, with feet 250 psi — — pass pass 300 psi — — pass pass 350 psi— — pass pass Two hour boiling water fail fail pass pass DimensionalStability 120° F. % wt. Change % length change % width change Warping100% Relative Humidity % wt. Change % length change % width changeWarping Large ball impact, inches to failure No feet 14 10 32, nofailure 32, no failure With feet 32, with pad — 32, no failure 32, nofailure Weathermeter HPUV Cigarette Burn, EN-438 Moisture Resistance

Example 2

A series of thermoplastic planks similar in design to the planks formedin Example 1 were connected together to create a flooring system. Thesplined system as set forth in FIG. 3 was used. In addition, acomparison was made with using no bonding agent and a flooring systemusing a bonding agent. The bonding agent, tetrahydrofuran (THF) wasapplied to all sides of the plank including the spline and grooves. Whenno THF was applied to the spline area, the bonding strength was anaverage of 1.73 pounds using the Instron test with the followingparameters 50 pounds full scale for the chart paper, 0.5 jaw speed, 3inch jaw distance, 1×5 sample, 156 mil spline thickness. When the sametype of extrusion plank had THF applied to the spline area, after 4hours curing, the bonding strength of the spline area was an average of18.1 pounds and after 24 hours curing, the bonding strength of thespline area was 39.1 pounds. The ends of the extrusion plank were testedfor bonding strength wherein the ends have no spline attachment andsimply butted against each other. There was no bonding strength when noTHF was present since there is nothing holding the edges of each planktogether. When THE was applied to the edges after 4 hours cure, thebonding strength was over 100 pounds using a 100 pound scale, and aftera 24 hour cure, the bonding strength was over 100 pounds using a 100pound scale. When the test was repeated with a 152 mil spline with THE,using the INSTRON test, after 24 hour cure, the bonding strength was anaverage of 45.37 pounds.

A rolling secretary test using 165 pounds was then used. In this test, a20 by 30 inch panel was used wherein a half of the panel was THF boundedover 24 hours and the other half of the panel had only splines holdingthe panels together. This panel was then laid on a carpet which causedmovement up and down on the panel. The product with the 156 mils splineseparated after 20 cycles and the other half of the product, which wassealed with THF, did not separate after 150 cycles. This was impressiveconsidering the panel was not glued down to any surface.

A second panel was then made and placed on a sterling board with feltshim (0.26 inch) and placed in different places on the PVC board. Thiswas done to cause unevenness in the subfloor. Upon doing the rollingsecretary test again, the planks did not separate with the THF present.

Both products were then tested by placing them on towels and water wasplaced on the end cuts and the spline area. After 10 minutes, the waterwas wiped and the THF end cut area had very little penetration of waterwherein the non-sealed area did show signs of leakage.

In the 75 pound slider test which was developed as a spline strengthtest, a 12 inch long spline was inserted into the tongue of a 12 inchplank and then a second plank was connected to the other side of thespline in order to connect two planks together. A hole was then drilledin the middle of one of the planks. With the two planks connectedtogether, 75 pounds was placed on the plank without the hole and a 50pound fish scale was hooked to the plank with the drilled hole andslowly pulled until the connected planks separated. With a 150 mil thickspline and a vertical gap thickness of PVC plank of approximately 154mil on average, the product pulled apart from the spline after a staticfriction reading of about 25 pounds initial pull wherein the pull wasdone on a Lauan substrate. Using a spline that was 156 mil thick, thespline went in with some tapping and the test was done both on a Lauanand Sterling board substrate which gave different readings on the fishscale. With respect to the Sterling board substrate (static friction) of40 pounds and (dynamic friction) of 35 pounds, the product did not pullapart. With respect to the Lauan (static friction) of 25 pounds and(dynamic friction) of 20 pounds, the product did not pull apart. A 159mil spline was then used which was hard to install due to the thicknessof the receiving tongue, in this test, Sterling (static friction) of 35pounds and (dynamic friction) pulled apart but took some effort and theproducts did not move at all. With respect to the Lauan (staticfriction) of 35 pounds and (dynamic friction) of 30 pounds, the productslid but no separation.

In view of the above testing, these examples show that the addition ofTHF as a bonding agent provides significant strength advantages to theoverall surface covering systems and also prevents water penetration tothe subfloor especially at the edges where there is no spline systemused.

Other embodiments of the present invention will be apparent to thoseskilled in the art from consideration of the specification and practiceof the present invention disclosed herein. It is intended that thespecification and examples be considered as exemplary only, with thetrue scope and spirit of the present invention be indicated by thefollowing claims.

1-46. (canceled)
 47. A thermoplastic laminate plank comprising: a rigidcore comprising at least one thermoplastic material, wherein said corehas a top surface and a bottom surface, and opposing sides; a printlayer optionally with an underlay affixed to said top surface of saidcore, wherein said print layer has a top surface and a bottom surface,wherein said print layer comprising a printed design; and a protectivelayer affixed to said top surface of said print layer, wherein saidthermoplastic laminate plank is not susceptible to damage caused bymoisture, wherein said core has a thickness of from about 5 mm to about20 mm, a width of from about 2 cm to about 30 cm, and a length of fromabout 30 cm to about 130 cm, said thermoplastic laminate plank has asurface tension of 34 dyne-cm or higher, and wherein said core has atongue design on at least one edge and a groove design on at least anopposite edge, wherein said at least one thermoplastic material ispolyvinyl chloride, wherein said thermoplastic material has a molecularweight as reflected by an inherent viscosity of from about 0.88 to about1.0 inherent viscosity.
 48. The plank of claim 47, further comprisingsaid underlay layer located and affixed between said bottom surface ofsaid print layer and said top surface of said core.
 49. The plank ofclaim 47, wherein adhesive is present between said core and said printlayer to affix said print layer to said core.
 50. The plank of claim 48,wherein adhesive is present between said core and said underlay layer inorder to affix said underlay layer to said core.
 51. The plank of claim47, wherein said core comprises at least one thermoplastic material andat least one plasticizer.
 52. The plank of claim 51, wherein said atleast one plasticizer is present with the thermoplastic material in anamount of less than about 1 phr.
 53. The plank of claim 47, wherein saidcore has a series of paralleled cavities which are separated by saidthermoplastic material.
 54. The thermoplastic laminate plank of claim47, wherein said thermoplastic plank has a doming distortion where thebottom ends of the plank are closer together.
 55. The thermoplasticlaminate plank of claim 47, wherein said surface tension is from 34dyne-cm to 45 dyne-cm.
 56. The thermoplastic laminate plank of claim 47,wherein said surface tension is 45 dyne-cm or greater.
 57. Thethermoplastic laminate plank of claim 47, wherein said groove design hasan internal depth dimension of from about 5 mm to about 12 mm and aheight of from about 3 mm to about 5 mm.
 58. The thermoplastic laminateplank of claim 47, wherein said thermoplastic laminate plank is suitablefor outdoor installation.
 59. The thermoplastic laminate plank of claim47, wherein said thermoplastic laminate plank has a growth in width andlength of 0.03% or less when thermoplastic laminate plank is exposed to90° F. and 100% RH.
 60. The plank of claim 47, wherein said protectivelayer comprises aluminum oxide.
 61. The plank of claim 47, wherein saidprotective layer comprises an aminoplast resin impregnated overlaypaper.
 62. The thermoplastic laminate of claim 47, wherein saidthermoplastic material comprises at least one thermoplastic resin, atleast one processing aid, at least one impact modifier, at least onelubricant, and at least one stabilizer.
 63. A surface coveringcomprising a plurality of thermoplastic laminate planks of claim 47joined together.
 64. The surface covering of claim 63, wherein saidsurface covering contains no T-moldings or expansion joints.
 65. Thesurface covering of claim 63, wherein said surface covering is a floorcovering that is a floating floor installation.
 66. A thermoplasticlaminate plank comprising: a rigid core comprising at least onethermoplastic material, wherein said core has a top surface and a bottomsurface, and opposing sides; a print layer optionally with an underlayaffixed to said top surface of said core, wherein said print layer has atop surface and a bottom surface, wherein said print layer comprising aprinted design; and a protective layer affixed to said top surface ofsaid print layer, wherein said thermoplastic laminate plank is notsusceptible to damage caused by moisture, wherein said core has athickness of from about 5 mm to about 20 mm, a width of from about 2 cmto about 30 cm, and a length of from about 30 cm to about 130 cm, saidthermoplastic laminate plank has a surface tension of 45 dyne-cm orhigher, and wherein said core has a tongue design on at least one edgeand a groove design on at least an opposite edge, wherein said at leastone thermoplastic material is polyvinyl chloride, and wherein saidthermoplastic laminate plank has a growth in width and length of 0.03%or less when thermoplastic laminate plank is exposed to 90° F. and 100%RH, wherein said thermoplastic material has a molecular weight asreflected by an inherent viscosity of from about 0.88 to about 1.0inherent viscosity.
 67. A spline having a top, bottom, and two opposingedges to connect flooring planks together comprising a spline having atapered or beveled edges to insert into a groove in a flooring plank andsaid spline having teeth on the top and bottom to engage said groove.